This invention relates to a tube-type reactor for carrying out endothermic chemical reactions with a gas by employing the thermal energy supplied by a hot pressurized gas, more particularly a noble gas, which is heated to a required temperature in a nuclear reactor.
One known form of a tube-type reactor comprises a bundle of vertical tube assemblies arranged within an internally-insulated pressure jacket. Each tube assembly includes a reactor tube, filled with a catalyst if required, and a concentrically-arranged cover tube which surrounds the reactor tube and forms an annular gap therebetween. A heat-yielding gas flows upwardly through this annular gap. The top portions of the cover tubes are collected together in mutual contact to form a bundle. An equilateral triangle is formed by imaginary lines extending between the center points of three tubes in mutual contact. The cover tubes have six slots uniformly distributed about their periphery to receive connecting elements that are secured by welding to permanently interconnect the cover tubes, thus forming a mounting plate assembly. The arrangement of parts is such that a minimum separation distance between the tubes is achieved to minimize the diameter of the bundle. When a tube-type reactor of this known form is placed in operation, the hot noble gas flows through the annular space between the cover tubes and the reactor tubes, whereby the gas also flows through the mounting plate assembly. Consequently, the mounting plate assembly is heated to a temperature corresponding to the temperature of the noble gas leaving the endothermic reaction region in the tube-type reactor. Therefore, the temperature of the noble gas should not exceed the temperature range of 650.degree. C. to 700.degree. C. to avoid weakening of the reactor components.
Recently, because of changes to the endothermic gas reaction process, a higher temperature of the noble gas discharged from the reaction region in the tubular reactor is required, namely, a temperature up to 800.degree. C. and even up to 850.degree. C. Under these conditions, the noble gas discharged from the reaction region in the tube-type reactor must be withdrawn from the reactor below the mounting plate assembly and the upper ends of the reactor tubes must be sealed in a gas-tight manner to the mounting plate assembly.
In another form of a known tube-type reactor, the reactor tube assemblies are mounted within bored openings formed in solid plates. The plates are insulated at their face surfaces which are directed toward the hot noble gas. In a further known form of a tube-type reactor, a double-mounting plate arrangement is used to form a cavity between the plates. A cold gas is passed through this cavity. However, it is a very difficult undertaking to effectively insulate the underside of the plate. Moreover, the risk of damage to insulation may easily occur during repair operations. The use of a double-mounting plate arrangement has the further disadvantage that undesirable thermal stresses occur in the plates.